1998 Ranger 2.5L, 5 speed. rebuilt engine 15,000 miles ago. To many new parts to list including, plugs wires lifters valves pistons, etc... my problem developed after 14,000 miles on rebuilt engine. I'm an experianced mechanic but never ran into anything like this! Tried changing lifters again, grinding .040 off the bottom of lifters on the effected cylinder with no effect. Oil pressure is normal with no spikes. Engine will start and run fine. Drive it easy still runs fine. Rev it a little at a stop or winding out the gears a little and it misses. A dead miss fire tracked down to number one cylinder. Depending on how hard you rev it i.e. if you rev it hard when it comes back down to idle it will quit. On imeadiate restart compression is 25 psi in number one cylinder. Let it sit a few minutes and it's back up to 133psi. I'm lost, I'm thinking lifters are pumped up to hard and holding the a valve open although it will not last long enough to do a leak down test. Any qurstions or suggestions? Thanks

 

Welcome to the forum

I would guess a valve/valve seat issue, not cam/rocker issue

These Lima(pinto) engines could get "tulipped" intake valves because of cylinder heat, not very common but have read about it, but I would expect full time loss of some compression.

Or exhaust valve seat could be loose after it gets hot, this was a TSB for the 3.0l engines, it would cause come and go compression issues
Never read about that on the Lima engines though

Cold test of all 4 cylinders may show #1 has a full time loss, compared to the other 3, then a cold WET test to see if its a valve issue

In any case I think you will need to pull the head to get to the bottom of intermittent compression

 

I checked compression cold & hot... cylinders are even within a few psi. The only time it loses compression is when I make it act up i.e rev let come down to idle. These are eight sparkplug heads. For a test I leave the compression gauge in the exhaust side. When I make it act up I shut it down and do a flood clear. the gauge reads 25 PSI. let it sit 30 seconds and it back up to 133 PSI. When i rebuilt the engine i also had new valves and seats installed. The problem is actually worse when ambient temperatures and engine temperature is lower. I asked the machinist who did my work and he agrees to my diagnosis of temporary lose of compression he has no idea why... thanks for your answer.

 

Then I would say you got a bad "new" valve or valve seat, can't see rings dropping the pressure that much.
My money would be on exhaust valve or seat

 

sounds like my issue...My compression is low on cylinder 1 balance tested all Injectors cyl#1 no idle drop when i pull power on injector same if I pull #1 plug wire . Floods at idle and dumps fuel "AND " all this is after changing out a new injector on #1. Compression checking is half as* cause I assume I'm testing a flooded bank with some gas in it so resting will be off anyway at that rate. So I tried to be sneaky and pull fuel relay start truck and hope all the gas burns or blows out exhaust to get a good reading. I gave up on it 2 weeks ago . I'm curious if it's just a valve truly and not rings

 

Valves are more likely to be the source of low compression in a cylinder if other cylinders are in "normal" range, 150-170psi
Rings tend to wear out together so overall low compression could mean ring issues

Fuel injectors all get 12volts with key on
The computer Grounds each injector to open it, so if an injector's wire to the computer is shorted to ground..................it will open with key on
You can test injector wires, Red wire is the 12volt wire, other color is the Ground, use ohm meter to engine metal, should show HIGH OHMs under 50 is a short or bad transistor in computer, unplug computer's large wiring connector and retest


There is a Fuel pump fuse and a fuel pump relay, pulling out either will turn off power to the fuel pump and simply cranking engine over a few times will cause 0 pressure in the fuel system, yes starting and letting it die will as well, there is no other source of pressure in the system, just the fuel pump

If you can cut off fuel system and then test compression in #1, and say you get 120psi DRY test
Then add a teaspoon of oil to #1 and retest WET, if its 130psi now then Valves are the problem, it is 150psi then it Rings
The oil seals the rings not the valves, slight increase is to be expect on any WET test, big increase means ring issue in that cylinder

 

the dry test has always yielded strange numbers on all 4 cylinders to the tune of what would almost be inoperable compression results but it don't run so bad that its REALLY Evident. I always get I think I recall 30psi cyl 1 90cyl2 60cyl3 and 130 cyl4 , this is with trying my best to make sure no fuel is in the cylinders. Someone mentioned jumped timing would be a possible to get such odd results. But the only tell tell is injector balance test cyl1 doesn't drop idle at all when I pull injector power or spark plug wire . Only way it could be injector related still is if #1 was not getting power or clogged but #1 injector is new as of 2 weeks ago and secondly all injectors ohms at 15ohms and plugs all have power.
I really wish I was missing or not seeing something stupid simple here, But with the smokey tail pipe on cold start with a little sputter of gas on ground after starting, a long with less power rich running and Balance test results seem to conclude valves or rings ,but if u look at the pics in my albums shows the antifreeze I drained recently could tell a lot about maybe some additives hiding a issue

 

A leak down test is the only thing I have not done and that would really tell a lot. I might try one more compression test but check the plugs for gas before I do the test so I know it's testing on dry cylinders

 

Does your oil smell like gasoline, it will if that much fuel is leaking into cylinders

Those compression test results are not valid

Remove 1 spark plug from each cylinder for the test, NOT optional, you need good crank speed to get good readings, so 0 compression on all cylinders except the one being tested

Press gas pedal to the floor and hold it down all the way for the test, this does two things, if gives engine full air flow and it shuts OFF fuel injectors(search Clear Flooded Engine, at our site)

Listen for 5 or 6 HITS of the compression stroke in the cylinder being tested, you will hear it
Compression gauges HOLD pressure, so will show highest pressure reached on one of the 5 or 6 hits, thats what you want
Release pressure and then test next cylinder

Repeat doing WET test this time.
I use a straw, dip it in the oil bottle then use finger at the top to hold it in straw then release oil into spark plug hole

 

are u saying pull 1 plug and test that particular cylinder while the other plugs remain in? Or must you have all the plugs pulled before ever testing a cylinder?
I always hold pedal to floor but I still don't believe clear flood mode doesn't work on my truck and I say that because I could never get it to restart after shutting it off from flooding on a hard start . Holding the pedal would not help . I learned to try the method of pulling the fuel relay to pass off the unspent fuel then locking the relay back in it starts.

recently I have been able to restart it a bit easier as if it isn't flooding and bad since I changed injector. I can't tell if its flooding out during actual running or during cranking after a engine shut off

 

For compression test only the one cylinder being tested should have compression
Other cylinders should have spark plug removed, if you have dual spark plugs just take out the easiest one to get to

Google: Ranger throttle cable mod

Simple fix and the only reason Clear Flooded engine wouldn't work, software is in all fuel injection computers, but pulling FP fuse or relay also works

If you had a leaking injector then with spark plugs removed you would see fuel spraying out of that cylinders open spark plug hole, definitive proof of open injector

If its a 1997 or earlier then could also be a leaking Fuel Pressure regulator(FPR), vacuum hose on FPR sucks fuel into the intake flooding engine

 

so I already did take the fpr vacuum line off the fpr "while running " I have good vacuum from the line and I have also removed the line from the fpr with the engine off "No fuel drppage out of line ".The fpr was replaced right before I bought the truck .
As for the cable mod I had my daughter wot open the linkage from the engine bay while I was holding the gas down to floor 3 weeks ago.No play in the cable .

if I wanna test #1 for stuck open injector I should just pull plug and turn key forward?
Why are the compression psi numbers so oddball as mention earlier . There so far off the truck should not run or move at all let alone idle . Something is causing wrong readings

 

Yes, if injector is leaking fuel then gasoline will spray out of an open spark plug hole, very easy to see

Some fuel will be present for startup, alot will be if injectors is leaking, so I would have all spark plugs removed for test(1 from each cylinder in your case, dual spark plug engine)

As far as the prior readings:
bad gauge or bad seal on the gauge
testing not done with all spark plugs removed(1 from each cylinder in your case, dual spark plug engine)
Rockers have come off of cam/valve centers

 

valve cover was off last week to inspect rockers all good new gasket at that point.
how exactly do i go about the checking for gas leaking injector prior to compression test ?
Should I crank with fuel relay in ? It would spray gas How do I set it up to test to see if it is open injector when it shouldn't be ?
its possible i had the wrong adapter for the test I was Leary about how much of a seal I was getting . The cyl plug valley is very narrow not very many 14mm adapters are narrow enough to reach down to seal agaist the plug entry. I still feel like that's the issue with the test results I tried 3 compression testers two were rented .

 

You would first check that each injector was NOT grounded with key on.
So hook up test light or volt meter to Battery +
Then with key on remove each injectors wire connector and test the NOT RED wire to see if its a ground, if one is then unplug computer connector and test again


Yes, if you are looking for leaking injector you would leave FP relay in and use Clear Flooded Engine, or unplug all 4 injector's wires
And yes 4 spark plugs would be out so you can see if fuel is spraying out of one of the spark plug holes

Not sure what to say about compression test results with bad seals, just ignore results on any cylinders you are not sure about
But with 4 spark plugs removed any cylinder you can test with a good seal should be 150psi +

 

Don't know how this thread got so far off subject from "temporary loss of compression " something I've never experianced in my 30+ years as a mechanic, I'm semi retired now. It is either broke or it isn't. Since this is my own truck I work on it as I have time. I always inspect the work done after a machine shop is done. After break in I had good compression. Still do. Unless you jab the throatle and it temporarily goes away. From 130 or so down to 0 at times. Let it sit and idle or shut it off for a few minutes and it comes back. I pulled the head and gave it a water test. It is seeping slightly on all the valves. Not just number 1. I took it to a machine shop and I'm having it gone over again. Valve job, new exhaust valves and seats. I like to see what's wrong and why it happened. Especially on a low mileage motor so I don't have the same problem 10,000 miles down the road. This is not the case with this one. I this truck run excellent, was well maintained. I did see someone else with the exact same problem in this forum, I think it was around 2010? No solution was given and they stopped writing. I will try to find a solution and keep you updated I'm sure this problem is no unique.

 

Never take anything for granted. I assumed I had a good head with new valve seats. Just replaced roughly 14,000 miles ago? Well... for some unknown reason the machinist installed soft seats! This sunk the valves in the head and as rpm increased the lifters got firmer lifting the valves off their seats when they were supposed to be closed. This was an expensive time consuming lesson I will not soon forget. My thanks to the people who tried to help.

 

Good find

Ford did that in the 3.0ls 2004 to 2006 heads

 

I'm over it. Its beyond my care.
I don't have the time or money or place or weather 7degree out to rebuild it . I'd just assume put in a v8 or buy a running 2 3. I've grown to hate this truck .
Or sell the truck it's too small of a cab to invest in for me as I've decided , If I get another ranger will be ext cab 4x4 .
if I ever get a small 2wd it will be a Ext cab Sonoma vortech.

 

Yes, cascade failures on used vehicles does happen, i.e. fix one thing and something else breaks, so one thing after another

One thing I have learned in my 40+ years of buying, driving and fixing cars and trucks, Ford does not build any good cars, and GM(chevy) can not build a good truck, not sure why this is but that's been my experience
So I now buy and drive Ford trucks and GM cars

 

I may do a vaccum guage test and or a compression leak down test last things that would conclude major issues. I just hardly care it starts drives stops but has the power of a go kart I loose speed and momentum in 4th 5th gear on a flat interstate and can only get up to 70 maintain it in 3rd gear .its equivalent to Go kart power .
AND I BURN GAS like a v10 that's no joke 5 or 6 mpg average easily worse then a 302 or 350 sub. Cold starts in morning it does plum out foggy smelly smoke that dont seem to be condensation . But it goes away after driving.
I wonder if it's really a bad maf throwing off the fuel trim extremely bad even though it Multimetered well.
I did a smoke test I found no leaks Smoke tests usually are good. I never messed with the dpfe. It's not spark at all every thing is new cool packs all of it. The tell tell is why do I get unbalanced cylinders test when I pull plug wire # 1 or #1 Injector plug . Something is not firing fuel.
I guess realizing that Its a deterrent to RIP apart my only daily driver now that it seems internal problem

 

Off engine topicnew symptom arose today while driving.
my speedometer all sudden is way off on the actual speed vs my phones GPS speed app. I noticed since u know I'm always struggling to drive 70mph the guage was buried at 85 lol.
So I tested it on way home more at lower speeds like 15mph on GPS Its not off as much only 3 -4mph 18mph on dash
when I am at 65 on the speedo my GPS speed is actually 50.
I know its a mechanical driven speedometer what could be the issue ? The 5 speed in 94 has a rpm and another cable that remove from driver side trans . Only time I had then off was when I did the slave cylinder change . It's been fine just flaked out on me. Plus the needle is wobbly during the spuratic changes

 

Shoulda started a new thread but while your here... I had an opal ralley do that once... there was a slight leak in the cable adapter on the transmission... the oil wicked up the cable into the speedometer head... It has a magnetic drum spinning inside another drum at very close tolerance... that's what moves your speedometer needle... the oily film on the inner drum caused just enough friction to make the speedometer read way to fast and act erratically.

 

interesting ... it seems odd the mechanical cable would even be open to any type seal at the trans where it is held in my a clip . I dont know how I would even begin to diagnose or prove your theory.. I probably won't lol.... the truck has so many other issues I see no point in worrying about this unless it was a easy fix
thanks again.